2. Field of the Invention
The present invention relates to a method of controlling an on-vehicle electric opening/closing body to detect blocking or pinching of a sliding portion generated during driving a motor so as to safely control opening/closing operations of the on-vehicle electric opening/closing body such as a vehicle sun-roof, or a vehicle power window.
2. Description of the Related Art
FIG. 1 is a circuit diagram showing a safety device for a vehicle sun-roof employing a conventional method of controlling an on-vehicle electric opening/closing body, which is disclosed in, for example, Japanese Patent Publication (Kokoku) No. 1-37291. In the drawing, reference numeral 11 indicates a motor to drive a sun-roof panel of the sun-roof serving as the on-vehicle electric opening/closing body. Reference numeral 30 indicates a driving circuit for the motor 11, 31 and 32 are relay contacts of the driving circuit, and 33 and 34 are relay coils. Reference numeral 40 indicates a series resistor connected to the motor 11 to detect driving current of the motor 11, and 50 is a switch to output an opening/closing starting signal for the sun-roof panel.
Reference numeral 60 indicates a filtering circuit to cut a high frequency component generated by the series resistor 40, and 70 is an amplifier to amplify an output signal from the filtering circuit 60. Reference numeral 80 indicates an adding circuit to add a predetermined value to an output signal VS from the amplifier 70 so as to set overcurrent of the motor 11, and 90 is a delay circuit to delay one output signal VD from the adding circuit 80.
Reference numeral 100 indicates an over load detecting circuit to detect over load of the motor 11 by taking, as inputs, the output signal VS from the amplifier 70 and an output signal VDD from the delay circuit 90, 101 and 102 are comparators of the over load detecting circuit 100, and 103 is a signal drive transistor. Reference numeral 110 indicates a memory circuit in which an amount of current (threshold) is stored at a time of pinching over load by receiving the other output signal VM from the adding circuit 80, 111 is a buffer of the memory circuit, 112 is a hold capacitor, 113 is a switching transistor, and 114 is a comparator. Reference numeral 120 indicates a stop circuit for the motor 11, and 121 and 122 are switching transistors of the stop circuit. Reference numeral 130 indicates an inverting circuit for the motor 11, and 131 is a transistor operated by a timer of the inverting circuit. Reference numeral 140 indicates a detecting circuit including a transistor 141, to detect a closing signal of the sunroof panel from the switch 50. Reference numeral 150 indicates a masking circuit to mask rush current at a starting time of the motor 11.
A description will now be given of the operation of the apparatus shown in FIG. 1. When the switch 50 is turned ON on the closing side to close the sun-roof panel, the transistor 141 in the detecting circuit 140 is turned OFF, and the switching transistor 122 in the motor stop circuit 120 is turned ON. Thus, current is present in the relay coil 34 in the driving circuit 30, thereby connecting the relay contact 32 to the ground so as to drive the motor 11.
The motor 11 is driven to flow its driving current in the series resistor 40, and voltage drop across the series resistor 40 generates voltage. The generating voltage is fed into the filtering circuit 60 as a driving current signal for the motor 11, and passes through the filtering circuit 60 to remove a high frequency noise component from the voltage. Thereafter, the voltage is input into the amplifier 70 to be amplified. The output signal VS from the amplifier 70 is supplied to the adding circuit 80 and the over load detecting circuit 100. The adding circuit 80 adds the predetermined value to the input signal VS to generate and output signals VD and VM. The signal VD is delayed by a predetermined time by the delay circuit 90 to become the signal VDD, and the signal VDD is supplied to the over load detecting circuit 100. Further, the signal VM is directly input into the memory circuit 110.
On the other hand, the switch 50 is turned ON on the closing side to actuate the timer of the masking circuit 150. The masking circuit 150 generates two kinds of output signals V200 and V300 depending upon timer operating periods (of 200 ms and 300 ms), and the output signals are respectively input into the memory circuit 110. That is, the signal V300 depending upon the timer operating period of 300 ms is input into the switching transistor 113 to turn ON the switching transistor 113 after an elapse of 300 ms from the starting time of the motor 11. Further, the signal V200 depending upon the timer operating period of 200 ms is input into a positive terminal of the comparator 114 to set output from the comparator 114 to ground voltage for a period of 200 ms from the starting time of the motor 11.
Therefore, the hold capacitor 112 in the memory circuit 110 is kept to the ground voltage for the period of 200 ms from the starting time of the motor 11, and is charged to voltage of the output signal VM from the adding circuit 80 for a period between time points of 200 ms and 300 ms so as to store the charged voltage as a threshold VMC. The threshold VMC is supplied to the over load detecting circuit 100. In the over load detecting circuit 100, the comparator 101 compares the output signal VS from the amplifier 70 with the output signal VDD from the delay circuit 90, and the comparator 102 compares the output signal VS with the threshold VMC from the memory circuit 110. When the load slides under a normal state, the output signal VS from the amplifier 70 is below the threshold VMC and the output signal VDD from the delay circuit 90. Consequently, the over load detecting circuit 100 outputs no detected signal, and the stop circuit 120 and the inverting circuit 130 are not actuated.
A description will now be given of the operation in case over load occurs during sliding. In this case, since overcurrent is present in the motor 11, the voltage drop across the series resistor 40 is increased to cause a rise of the output voltage VS from the amplifier 70.
At this time, the signal VDD is delayed by the delay circuit 90 to rise slower than a varying time of the signal VS, resulting in a time zone in which the signal VS exceeds the signal VDD. The output signal VS from the amplifier 70 may increase to exceed the threshold VMC.
When the output signal VS from the amplifier 70 exceeds at least one of the signal VDD and the threshold VMC as set forth above, in the over load detecting circuit 100, output from one or both of the comparators 101 and 102 is set to the ground voltage, and the transistor 103 is turned OFF.
Thereby, in the stop circuit 120, the switching transistor 121 is turned ON, and the switching transistor 122 is turned OFF. When the switching transistor 122 is turned OFF, no current is present in the relay coil 34 in the driving circuit 30. Thus, the relay contact 32 is turned OFF to interrupt driving current so as to stop the motor 11. On the other hand, the switching transistor 121 is turned ON to actuate the timer in the inverting circuit 130, and to turn ON the transistor 131 therein, resulting in current in the relay coil 33 in the driving circuit 30. Therefore, during the timer in the inverting circuit 130 is operated, the relay contact 31 is connected to the ground, and reverse driving current is fed into the motor 11 to reversely rotate the motor 11 for the feeding period.
The conventional method of controlling the on-vehicle electric opening/closing body has the following problems. That is, when variation in the driving current of the motor 11 is slower than a time constant of the delay circuit 90, the output signal VS from the amplifier 70 never exceeds the output signal VDD from the delay circuit 90. Then, there is one problem in that over load can not be detected. In addition, any obstacle may be present while the sun-roof panel is slid immediately after a masking period of 200 ms from the starting time of the motor 11, that is, any obstacle may be present for the period between the time points of 200 ms and 300 ms after the starting time. In this case, overcurrent in the motor 11 due to the obstacle increases the output signal VM so that the threshold VMC stored in the memory circuit 110 is set to a higher value than would be in a normal state. Accordingly, a difference between the signal VS and the threshold VMC is thereafter increased, and the signal VS never exceeds the threshold VMC even if the over load occurs during sliding the sun-roof panel after the threshold VMC becomes higher. Thus, there are other problems in that the over load can not be detected, resulting in a complicated and dangerous opening/closing control for the on-vehicle electric opening/closing body.